1. Field of the Invention
The present invention generally relates to a hybrid vehicle driving device and, more particularly, to a hybrid vehicle driving device for a hybrid vehicle making an engine and a motor cc-work as a drive source of the vehicle.
2. Description of Related Art
Hybrid vehicles making an engine and a motor co-work as a drive source of the vehicle are known in the art. A battery for supplying electric power to the motor is mounted on a vehicle body, and the vehicle is configured so as to further improve the energy efficiency by charging the battery by making the motor regenerate the electric power in decelerating, traveling on a descending slope, and the like.
In Japanese Patent No. 3967309, a configuration of a scooter type hybrid two-wheeled vehicle is disclosed in which an engine and a motor are stored in a unit swing that is swingably attached to a vehicle body frame and that pivotably supports a rear wheel. This hybrid two-wheeled vehicle is configured so that the drive force of the engine is transmitted to the rear wheel through a belt type continuously variable transmission, whereas the drive force of the motor disposed in the vicinity of an axle of the rear wheel is transmitted to the rear wheel without passing through the continuously variable transmission.
As described above, in the hybrid vehicles, although the energy efficiency can be improved by executing electric power regeneration using the motor as a generator in decelerating, traveling on a descending slope, and the like, it is known that the electric power generation efficiency in electric power regeneration is high in a specific rotational speed range according to the characteristics of the motor and becomes lower as the rotational speed departs from the specific rotational speed range. However, according to the technology described in Japanese Patent No. 3967309, because the speed reduction ratio between the motor and rear wheel is fixed, the rotational speed of the motor in regenerating charging is proportional to the rotational speed of the rear wheel, and it is not possible to execute regenerating charging positively selecting a rotational speed range where the electric power generation efficiency is high.